e 
J. M. Safford on the Upper Silurian Beds of Western Tenn. 207 
No.4. Variegated Limestone.—This bed, tic ast T notice, rests 
directly upon the Hudson river rocks. The junction is well 
seen at Clifton and below that place, for several she along the 
eastern bank of the Tennessee river. This bed is seen in the 
glade region occupying generally a ‘low position. Outside of 
Wayne and Hardin counties its base is rarely seen. The vicin- 
ity of Clifton is the most favorable ot for studying the entire 
bed, that has come under my observat 
It is easily recognized by ‘aterstratified brownish-red layers, 
some of which, when crinoidal, furnish a pies good marble. 
It is, however, often argillaceous and erum 
Its red color, due to sesquioxyd of iron, may indicate its 
Clinton affinitie 
This bed is, in sb penlaind: comparatively barren in fossils. Occa- 
sionally its layers are crinoidal. Atrypa reticularis, and several 
species of orthocerata are met with. At Clifton, the base of the 
bed, the entire mass, is exceedingly rich in individuals of several 
species of orthoceras and in large erinoidal stems and roots. The 
sponges especially are abundant 
oO. ray Limestones and Shales, or the Sponge-bearing Bed. 
—This is the division to which Dr. Roemer’s fauna belongs. . It 
is a series of gray crinoidal limestones and calcareous shales, the 
latter often predominating. On the sloping marly glades the 
layers of limestone frequently crop out in two or three success- 
ive ledges separated by masses of shale. Thin layers of chert 
often occur interstratified with the limestone. Fossils aboun 
among them Astraeospongia meniscus is shi characteristic, 1 in 
fact the mass might well be called the Meniseu: 
The general thickness of the bed is from m 80 to 100 feet. In 
above it is given at 90 feet; it is quite possible, however, that a 
portion of the overlying bed (as in it, at this point, no character: 
istic fossils were observed) ought to be included, thus making 
the thickness to a small extent greater. 
The e-bearing Bed is the prevalent rock of the glades_ 
Spong 
in Hardin, Wayne, Deceit and Perry counties. It also oti : 
to some extent, in Humphreys, Benton and Henry. et, 
Nearly all of the species given by Dr. Roemer in his mono 
graph are found in this bed. There are a few, bait which, 
so far as my observations extend, are confined to he bed next 
above, naviee.} been seen, in place, only in these wie 3 
important, perhaps, i is Pentamerus galeatus. Pate” weropleure 
(S. ie ene of the monograph) although 1 
@ ove oye 
Cileels faeces a is s the ones wae C. Atnericant: 
